Pulp Pathogenesis PDF

Pathogenesis of Pulp/Periapical Dz endo “within” dontic “tooth” Why does anyone need a root canal? Due to an Infection Endo Procedural Overview • Create opening in infected tooth • File to remove the infection • Use plugger to fill canals w gutta percha • Seal opening, place any other retentive meas...

Pathogenesis of Pulp/Periapical Dz endo “within” dontic “tooth” Why does anyone need a root canal? Due to an Infection Endo Procedural Overview • Create opening in infected tooth • File to remove the infection • Use plugger to fill canals w gutta percha • Seal opening, place any other retentive measures • Crown When it comes to ‘dark teeth’ and ‘fistulas’: • Dark teeth can be: o Necrotic o Stained from trauma (internal bleeding gets into the dentinal tubules) • Pts with true ‘dark lesions’ shouldn’t feel cold when pulp vitality is done o Should indicate a necrotized root o Response to pulp vitality could indicate lesion is actually a differential, OR it could be a partially necrosed tooth (multi-rooted with still vital roots) • Fistulas may not be a true fistula as much as they are pockets of infection Why cant we simply take an antibiotic and kill the bacteria? • Only place in the body where tissue is firmly encased in a hard structure • Inflammation and swelling creates pressure that damages the blood supply and nerve Pathogenesis of Pulp and Periapical Diseases Histology and Physiology of Normal Dental Pulp • The Pulp is a unique connective tissue with vascular, lymphatic, and nervous elements that originates from neural crest cells • Resides in rigid chamber of tooth wall • Contains: o Odontoblasts § Specialized cells w a secretory function § Form dentin § Interact w dental epithelium early in tooth development to initiate the formation of enamel o Fibroblasts o Undifferentiated mesenchymal cells o Collagen type I and II o Proteoglycans o Glycoproteins o Water Pulp Dentin Complex (Synergistic) • Odontoblasts line the periphery of the pulp tissue and extend into the dentin o No dentin w/o odontoblasts o Pulp requires protection from dentin and enamel • Impacts on dentin may affect the pulp, and pulpal disturbances can affect quality/quantity of dentin • The cell rich zone of the pulp has a low level of immune cells present o Can fight of some infection but should not be relied upon • It can take 2-3 yrs for the root/pulp to fully form in a tooth, and the • Pulp chamber regress as odontoblasts form more dentin to better shield the pulp from external stimuli Innervation of the Pulp 2 main fibers: • A Delta fibers (peripheral, out into tubules) o Sharp response to thermal change o Extend between the odontoblasts o Lose their myelin sheath (slows down the nerve transmission as they die) o Extend to a distance of 100 to 200 μm into the dentinal tubules • C fibers (deep in tissue) o Unmyelinated o Dull ache that affects patients with symptomatic irreversible pulpitis Irritation • Irritation response decreases with maturity due to vasculature changes • Young teeth have ample blood supply, decreases as apices close • Rxn of the pulp to irritants is dictated by the type/duration of stimulus • Classified as Living (microbial) or Non-living (Mechanical, Thermal, Chemical) It takes 48hrs for a pt to feel an Mechanical irritants • Pulp irritation increases as prep depth increases inflammatory response o Dentin permeability > when closer to pulp o Can be caused by: § Deep scaling It takes 48hrs for antibiotics to kick in § Curettage § Removal of tooth structure w/o proper cooling • Periapical tissues can be mechanically irritated o Nerves around roots of teeth are for proprioception o Inflammation in periapical tissue affects the nerves, cause pressure sensitivity o Can be caused by: § Impact injuries § Hyper-occlusion § Over-instrumentation of root canals § Root perforation, over-extension of root canal filling materials Chemical Irritants • Antibacterial agents, irrigating agents, and chemicals present in desensitizers, liners, bases and restorative materials can cause inflammatory changes due to cytotoxicity Antibacterial Agents Irrigated Agents • Silver nitrate • Alcohol • Phenol w or w/o camphor • Chloroform • Eugenol • Hydrogen Peroxide • Various acids Microbial Irritants • Most significant cause of inflammation is microbial • Even superficial carious lesions in enamel are capable of attracting inflammatory cells in the pulp. • Initial rxn of the pulp causes immune response o Causes focal accumulation of chronic inflammatory cells (macrophages, lymphocytes, plasma cells) o Tissue can remain inflamed for extended periods and can undergo eventual/rapid necrosis Microbiology of Root Canal Infections • Normal conditions -> pulp and dentin isolated from oral microorganisms by enamel, cementum • Any breach of enamel/cementum exposes the pulp to the outside environment o Increases infection risk o Risk increases more depending on depth of lesion (dentinal tubules widen closer to pulp) Caries are the most common cause of pulp exposure • Factors that dictate severity of pulp response: o Virulence of microorganisms Infections always go o Ability to circulate inflammatory fluids to avoid increased intrapulpal pressure from crown to apex o Host resistance o Lymphatic drainage o Other irritants, microorganism byproducts, products from necrosed pulp spreading from crown to root • Bacterial contamination must be present for pulpal/periapical pathoses to develop o Endo infections classified based on anatomical location (extraradicular/intraradicular) o Intraradicular infections (biofilms) considered primary cause of endo treatment failure § Microorganisms in apical root canal, apical deltas, lateral canals can cause long standing infections § Apical biofilms have access to nutrients to facilitate growth, causes extended host response and avoids healing • Goal of RCT is to remove microorganisms from root canal system o Failure of aseptic technique can introduce microorganisms into the canal o From lack of rubber dam use, leaking rubber dam, contaminated files and instruments, etc Endodontic Infections are Biofilm Infections • Biofilms are micro-colonies of bacteria that irreversibly attach to a substratum, to dentin, or to itself • Heterogenous matrix that will act as a physical barrier to antibiotics and disinfectants o Hard to remove but must be removed to achieve healing Microbes in Endodontic Infections • Primary root canal infections have multispecies populations o Facultative o Anaerobic gram positive, gram negative o Spirochetes o Yeasts o Unidentified species • Microbiome of carious dentin leads to endo infection (pulpitis and subsequent endo infections) consists of: o Lactobacilli o Gram Neg bacteria • Epstein Barr (EBV) can be assc with irreversible pulpitis, apical periodontitis • Papilloma Virus and Human Herpes Virus can be found in exudates from acute apical abscesses Microorganism Canal Infiltration • Causes of infiltration btwn appointments: o Leakage/loss of temporary filling o Cracked tooth o Tooth left open • Other causes: o Not using a rubber dam o Caries left in tooth o Delay in getting permanent restoration Survival of Pulp under Severe Inflammation Responses Based on Apex Formation Mature Apex Immature Apex • Less likely to retain vital pulp • More likely to retain a vital pulp • Less circulation due to closed apices • More collateral circulation Pulpal Diseases (1-4-24) • Inflammatory responses begin in the pulp in locations corresponding to the location where the irritant reaches it o Ex. Incipient lesions can have inflammatory responses in pulp at the end of associated dentinal tubules o Inflammatory response will spread through coronal pulp as lesion deepens until pulp is invaded § Severe inflammation will occur at this point • Inflammatory response can be reversed when lesion can be treated conservatively or can progress to irreversible (requires professional intervention) o Degree of irritant has a positive correlation with level of inflammation • Unlike other connective tissues, the dental pulp lacks collateral circulation, it is confined within rigid dentinal walls. • Therefore at a specific point in the disease process, the inflammation changes from reversible (one that would respond favorably to conservative treatment and heal) to irreversible pulpitis. • The transition of reversible to irreversible pulpitis is important to identify because it determines the optimal treatment. • Inflammatory mediators seen in assc with increased pulpal pain in pts with symptomatic irreversible pulptis o Prostaglandins If our apex is closed and we can just remove the pulp o Neuropeptides and be fine, why do we have to have a pulp? o Bradykinin o Cytokines Loss of pulp = loss of receptor nerves. o Chemokines o Matric metalloproteinases Care must be taken to ensure undetected future • Pulp nociceptors increase excretion of Substance P and CGRP decay doesn’t occur. under inflammation o Lowers pain threshold Teeth can become more brittle when nerves removed. o Increases blood vessel permeability to inflammatory cells Pulp Stones (not pathologic) • Radiographic evidence of increased mineralization causing deposits of hard dentinal tissue in pupal space o Nerves signal for more protection, causing an increased lay down of dentinal tissue in pulp space o Associated with: § Trauma Even when it looks like there is no pulp canal § Bruxism present, there is ALWAYS some degree of pulp § Caries tissue present, even if it is just 1 cell wide § Deep restorations § Cardiovascular dz § Statin meds • Not considered pathologic Resorption • Pulp can undergo internal resorptive defects • Initiated by osteoclasts or odontoclasts (not normal inhabitant of healthy pulp) o From monocytes o Mediators of bone turnover seen in PDL, alveolar bone o Expand in size to form resorptive lesion o Not commonly found in healthy pulp • Resorption (internal or external) is pathologic even w no symptoms Process of Periapical Healing • Once irritants removed: o Inflammatory response decreases o Tissue forming cells increase (fibroblasts, endothelial cells) o Resorbed bone begins to be replaced o Resorbed cementum, dentin is repaired via cellular cementum o PDL (first affected tissue) will be restored last Calcification likes to lay down over furcations of bifurcated/trifuracted roots and deep in root canals of anterior teeth in a coronal to apical direction Factors Influencing Healing • Inherent loss of host factors (impaired blood supply, leukopenia, malnutrition) • Corticosteroids • NSAID (prevent inflammation before it happens) • Systemic dz (ex. Diabetes Mellitus) Notes from Lab: • EDTA, which is used to irrigate root canals, does not dissolve tissue • Root canal sealer paste is what seals the roots off from bacteria • Gutta percha without sealer will lead to a failed RCT